Background: Aging population is progressively increasing. Older adults suffer from the different chronic health conditions such as hypertension. Behavior change is a key strategy for effective hypertension management. Successful behavior change necessitates the adequate self-efficacy. Objectives: This study aimed to evaluate the effects of a self-management program based on the 5 A's model on self-efficacy among the older men with hypertension. Methods: This randomized controlled trial was conducted in 2016u2017 on older men with hypertension in Ramsar, Iran. In total, 60 eligible participants were randomly allocated to an intervention and a control group. The participants in the intervention group were offered a self-management program based on the 5 A's behavior change model. Data were collected using a demographic questionnaire, a hypertension assessment form, the Self-Efficacy for Managing Chronic Disease Scale, and the hypertension Self-Efficacy Scale. Self-efficacy scales were completed for participants both before and 12 weeks after the intervention onset. The paired- and independent-sample t, Wilcoxon signed-rank, MannuWhitney U, and Chi-square tests were used in the data analysis. Results: The pretest mean scores of hypertension self-efficacy in the intervention and the control groups were, respectively, 48.62 11.71 and 44.65 15.4, which significantly increased to 79 13.13 and 62.06 15.38 at posttest (P < 0.001). Moreover, the pretest mean scores of chronic disease management self-efficacy in these groups significantly increased from, respectively, 5.64 1.28 and 5.35 1.40 at pretest to 8.05 1.29 and 6.12 1.48 at posttest (P < 0.001). The pretestuposttest mean differences of the mean scores of both types of self-efficacy in the intervention group were significantly greater than the control group (P < 0.001). Conclusion: The self-management program based on the 5 A's model is effective in significantly improving the self-efficacy among older men with hypertension.